Parkinson's disease and melanoma – a deadly form of skin cancer – may be linked, warn scientists who found that each disorder raised the risk of the other by four times.

Researchers from Mayo Clinic in the US found that patients with Parkinson's were roughly four times more likely to have had a history of melanoma than those without Parkinson's.

They also found that people with melanoma had a fourfold higher risk of developing Parkinson's.

Researchers examined the prevalence of melanoma in 974 patients with Parkinson's and compared with 2,922 residents without Parkinson's.

They also identified 1,544 cases of melanoma and determined the 35-year risk of Parkinson's in those patients compared with the risk in the same number of people without melanoma.

They found that the results supported an association between Parkinson's disease and melanoma.

“It is likely that common environmental, genetic or immune system abnormalities underlie both conditions in patients who have both, but more research is needed to confirm that and refine screening recommendations,” researchers said.

“If we can pinpoint the cause of the association between Parkinson's disease and melanoma, we will be better able to counsel patients and families about their risk of developing one disease in the setting of the other,” said Lauren Dalvin, from Mayo Clinic.

The study was published in the journal Mayo Clinic Proceedings.